Momentum Multiple Choice/True False
Modified True/False
Indicate whether the sentence or statement is true or false. If false, change the identified word or phrase to make the
sentence or statement true.
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1. Linear momentum is a scalar quantity. _________________________
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2. The impulse is always in the same direction as the net force. _________________________
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3. The average force accurately represents the actual force during a collision.
______________________________
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4. If the net force acting on a system of objects is zero, the linear momentum of the system is conserved for any
number of objects. _________________________
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5. In a one-dimensional linear momentum question, only the speed is important to know for colliding objects.
______________________________
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6. Momentum is not conserved in all collisions. _________________________
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7. The direction of the net force and the direction of the impulse are always the same.
_________________________
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8. A single train car loaded with sand travels by itself along a horizontal frictionless track at a constant speed. A
hole is punctured in the bottom of train and the sand slowly leaks out causing the train car to speed up.
_________________________
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9. Two blocks of different mass are attached by a string and slide along a horizontal frictionless surface at a
constant speed. When the string is cut, the speed of the larger block will stay the same.
_________________________
____ 10. A system consists of a sliding wooden block on a wooden plank. The plank is mounted on frictionless wheels.
Friction causes the block to slow down and stop, so momentum of the system is not conserved.
_________________________
____ 11. It is possible that an object can receive a larger impulse from a small force than from a large force.
_________________________
____ 12. During a collision of a bullet and a wooden block, the force of friction can be neglected because the
interaction is so brief. _________________________
____ 13. When you triple the velocity of an object of constant mass, you also triple the momentum.
_________________________
____ 14. Momentum cannot be used during car collisions that involve cars with “crumple zones.”
_________________________
____ 15. Knowledge of momentum has not reduced the number of deaths in vehicular accidents in the past 10 years.
_________________________
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
____ 16. A 5.0-kg cat travelling at 1.3 m/s [E] has a momentum of
a. 6.5 m/s [E]
d. 3.8 m/s [W]
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b. 6.5 m/s [W]
e. none of the above
c. 3.8 m/s [E]
A bobsleigh and its riders have a combined mass of 598 kg. They cross the finish line with a velocity of 125
km/h [forward]. The momentum of the team and the bobsleigh at the finish line is
a. 4.78 kgm/s [forward]
d. 7.48  104 kgm/s [forward]
b. 17.2 kgm/s [forward]
e. 2.69  105 kgm/s [forward]
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c. 2.08  10 kgm/s [forward]
A bullet with a momentum of 2.8 kgm/s [E] is travelling at a speed of 187 m/s. The mass of the bullet is
a. 0.015 g
d. 67 g
b. 0.067 g
e. not enough information
c. 15 g
During collisions, it is often acceptable to ignore the force of gravity on an object. This is because
a. the time the other forces act is so short that we can ignore the force of gravity
b. the force of gravity is always acting on the object and we only consider change
c. the object may be in space and the gravitational force does not exist
d. the collision is often perpendicular to the force of gravity, so Fg does not play a role
e. the force of gravity is insignificant compared to the other forces acting on the object
A net force of 12 N changes the momentum of a 250-g ball by 3.7 kgm/s. The force acts for
a. 0.31 s
d. 3.2 s
b. 0.81 s
e. 44 s
c. 1.2 s
A 2200 kg car starts from rest and speeds up to 12 m/s in 5.2 s. The net force acting on the car is
a. 1.8  102 N
d. 5.1  103 N
2
b. 4.2  10 N
e. 1.4  105 N
c. 1.1  104 N
A car with a mass of 1800 kg slows from 42 km/h [E] to 28 km/h [E]. The impulse from the brakes is
a. 2.5  104 Ns [E]
d. 2.1  104 Ns [W]
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b. 2.5  10 Ns [W]
e. 7.0  103 Ns [W]
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c. 2.1 10 Ns [E]
A 1.5-kg bird is flying at a velocity of 18 m/s [22º above the horizontal]. The vertical component of its
momentum is
a. 10 m/s [up] (2 significant digits)
d. 17 m/s [up]
b. 6.7 kgm/s [up]
e. none of the above
c. 25 kgm/s [up]
A 1.5-kg bird is flying west at a velocity of 18 m/s [22º above the horizontal]. The horizontal component of
its momentum is
a. 10 m/s [W] (2 significant digits)
d. 17 m/s [W]
b. 6.7 kgm/s [W]
e. 17 kgm/s [E]
c. 25 kgm/s [W]
A bullet with a mass of 28 g is fired from a 2.8-kg gun that is stationary, but free to recoil. After the bullet is
fired, the gun is observed to be moving at 1.4 m/s [left]. The velocity of the bullet is
a. 140 m/s [left]
d. 71 m/s [left]
b. 140 m/s [right]
e. 71 m/s
c. 71 m/s [right]
A shell is fired from a gun mounted on a battleship. Which of the following statement is NOT true?
a. There will be a force to push the boat in the opposite direction of the shell.
b. The recoil spring on the barrel is to minimize the force on the deck of the ship.
c. Neglecting fluid friction, the momentum of the boat and shell have the same magnitude.
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d. To calculate the speed of the boat we would need to know the recoil length of the gun.
e. A larger mass of shell will increase the recoil force felt by the ship.
A person jumps from an airplane and reaches terminal speed.
a. The momentum of the jumper is constant because there is no external net force.
b. The momentum of the person–Earth system is not conserved because of air friction.
c. When the chute is opened, the force disrupts the conservation of momentum of the
person–Earth system.
d. two of A, B, and C are correct
e. all of A, B, and C are correct
An arrow slows down from 43 m/s to 28 m/s as it passes through an apple. If the 493-g apple was originally at
rest and sped up to 0.44 m/s, the mass of the arrow is
a. 5.0 g
d. 29 g
b. 7.7 g
e. 7.7 kg
c. 14 g
A boy throws a 15-kg ball at 4.7 m/s to a 65-kg girl who is stationary and standing on a skateboard. After
catching the ball, the girl is travelling at
a. 0 m/s
d. 3.2 m/s
b. 0.88 m/s
e. 4.7 m/s
c. 1.1 m/s
A goalie standing on a frictionless surface catches a 270.0-g puck travelling at 95.0 km/h. After catching the
puck, the goalie is moving at 8.90 cm/s. The mass of the goalie (including equipment) is
a. 75.2 kg
d. 84.2 kg
b. 79.8 kg
e. 91.7 kg
c. 80.1 kg
A 55-kg person carrying a 5.0-kg ball slides along a horizontal frictionless surface. He tosses the ball
perpendicular to his direction of travel relative to himself.
a. His path will not change.
b. The ball will have a smaller angle from the original path than he will.
c. His speed does not change.
d. He speeds up.
e. He slows down.
A 55-kg person carrying a 5.0-kg ball slides along a horizontal frictionless surface. He tosses the ball forward.
a. His path will not change.
b. The ball will have a smaller angle from the original path than he will.
c. His speed does not change.
d. He speeds up.
e. He will most likely stop moving forward.
A moving curling stone, A, collides head on with a stationary stone, B. Both stones are of identical mass. If
friction is negligible during this linear elastic collision,
a. stone A will slow down
b. after the collision, the momentum of stone B will be less than that of stone A
c. both stones will come to rest shortly after the collision
d. after the collision, the kinetic energy of the stone B will be less than that of stone A
e. after the collision, stone A will have a speed of zero
If an arrow’s mass is doubled and the speed is halved, the momentum is changed by a factor of
a. 0.25
d. 2
b. 0.5
e. 4
c. 1
____ 35. A car (of constant mass) doubles its speed while driving up a hill sloped at 45º. The factor by which its
momentum changes is
a. 0
d. 3
b. 1
e. 4
c. 2
____ 36. A car (of constant mass) doubles its kinetic energy while driving down a hill sloped at 45º. The factor by
which its momentum changes is
a. 1
d. 2.8
b. 1.4
e. 4
c. 2
____ 37. A ball rolling down a hill doubles its speed but reduces its gravitational energy to one-fifth its starting value.
The factor by which its momentum changes is
a. 0.4
d. 2
b. 1
e. 10
c. 1.4
____ 38. A ball rolling down a hill doubles its momentum but reduces its gravitational energy to one-third its starting
value. The factor by which its kinetic energy changes is
a. 0.66
d. 4
b. 1
e. 6
c. 2
____ 39. A 72-kg girl on a skateboard doubles her kinetic energy coasting down a hill.
a. Momentum is conserved.
b. The increase in kinetic energy is offset by a decrease in momentum.
c. The momentum will also double.
d. Her momentum does not change.
e. none of the above
____ 40. A sabotaged curling stone explodes into three pieces as it travels across the ice. Neglecting the force of
friction,
a. all three pieces will travel at the same speed
b. the magnitudes of the momenta for each piece will be the same
c. an external net force had to act on the stone to accelerate the three pieces
d. the components perpendicular to the original motion must add up to zero
e. momentum is not conserved because of the small explosive charge
____ 41. Two young sisters with a combined mass of 75 kg ride on a cart of mass 30.0 kg travelling at 2.0 m/s. If they
jump off together so they land with zero speed relative to the ground, the change in speed of the cart is
a. 0 m/s
d. 5.0 m/s
b. 2.0 m/s
e. 7.0 m/s
c. 4.0 m/s
____ 42. A force of 4.0 N [S] is applied to a 2.0-kg block sliding west at 3.0 m/s on a smooth surface. The puck will be
moving exactly south-west after
a. 1.1 s
d. 2.8 s
b. 1.5 s
e. 4.2 s
c. 2.1 s
____ 43. A woman of mass M is at rest on a frictionless skateboard of negligible mass. She throws a cement block of
mass m with a velocity v relative to the ground. After the throw, her velocity relative to the ground is
a. –mv
d. Mv
b.
e.
c.
____ 44. A two-dimensional collision occurs as shown below.
Which vector below most closely represents the new velocity of P?
a. A
d. D
b. B
e. E
c. C
____ 45. Two objects of equal mass with the speeds indicated by the vectors below, collide and stick together.
Which vector below best represents the velocity of the combined objects after the collision?
a. A
d. D
b. B
e. E
c. C
____ 46. To compare the kinetic energies of two objects, you must know
a. their masses
d. the forces acting on them
b. their velocities
e. the work done to stop each of them
c. their momenta
____ 47. When you catch a fast-moving baseball, your hand hurts less if you move it in the direction of the ball
because
a. the ball changes momentum more slowly
b. the force applied is smaller
c. you decrease the impulse required to stop the ball
d. two of A, B, and C
e. all of A, B, and C
____ 48. When a baseball bounces on the ground
a. momentum is conserved in the Earth–ball system
b. the impulse is the same as if the baseball landed without bouncing
c. it leaves the surface with the same speed that it impacted the surface with
d. kinetic energy is imparted to the ground
e. the force applied by the surface is smaller than if it didn't bounce
____ 49. Two objects strike a glancing blow. The diagram below shows the momenta of some of the objects are shown
before and after the collision.
Which vector best represents the momentum of object P after the collision?
a. A
d. D
b. B
e. E
c. C
____ 50. A gun is mounted on a wooden plank. The plank is stationary and is mounted on frictionless wheels. A heavy
wooden block is set in front of the gun, and the gun is fired into the wooden block, which then slows to a stop
due to friction between the block and the plank.
a. The plank does not move.
b. Momentum is not conserved because of the frictional force.
c. The speed of the plank is zero immediately after the collision between the bullet and
block.
d. The plank will have shifted position relative to its starting point.
e. Kinetic energy is conserved because the speed of the system is zero before and after the
collision.
____ 51. The collision time between a bullet and a block of wood is best measured in
a. nanoseconds
d. seconds
b. microseconds
e. hours
c. milliseconds
____ 52. Without knowing any other information than is given in the diagram below, which deductions could be true?
a. The eastbound car was travelling faster.
b. The northbound car was lighter.
c. Both cars had the same speed.
d. two of A, B, and C
e. all of A, B, and C
Momentum Multiple Choice/True Falso
Answer Section
MODIFIED TRUE/FALSE
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F, vector
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